Fan blade



Sept. 30, 1930. l w, H Q NESS 1,777,013

FAN BLADE Filed Sept. l, 1928 4 In this specification,

might accumulate.

WILLIAM HENRY CLAY miss, or.

ing from the essence Patented ,Sept 30, 1930 UNITED STATES PATE NT orrlcaf- FAN CORPORATION, OF-LOS ANGELES, CALIFORNIA FAN BLADE Application med September and the accompanymg drawing, I shall describe and show a preferred form of my invention and specifically mention certain of its more important objects. I do not limit myself to the forms disclosed, since various changes and adapta' tions may be made therein, Without` departof my invention as hereinafter claimed; and objects and advantages, other t-han those specifically mentioned, are included within its scope.

My invention relates to fan blades and more particularly to a hub construction for such blades.

A further object ofthe invention is to provide a hub construction for fans electrically or otherwise driven, which is free from under-cuts or recesses of any kind within which dirt, dust particles, or other materials suspended in the atmosphere This improvement in the construction of the hub 'adapts the fan for use in rooms where paint is sprayed, and also for use in Ventilating rooms containing dust-laden air of any kind such as is often encountered in various mills and factories.

object of my invention is also to provide a hub for fan blades which will reduce to a minimum air turbulence at the hub thus making inappreciable the sound caused by operating the fan and also eliminating a negative thrust of air upon the fan, especially adjacent to the axis of rotation thereof, thus producing a maximum ositive air thrust and securing ultimate e ciency. A

Another object of the invention is to pro videa fan which can be readily cast in one piece out of any kind of metal thereby economizing material and effecting a valuable reduction in Weight. In this connection a valuable feature is the readiness with which` 1, 192s. seiai No. 303,517.

generally revalentin the hub construction of fan bla es. Other objects and advantages may hereinafter appear when the invention is contemplated in the light of the accompanying detailed description, when considered in reference tothe drawings, and with regard to the salient points thereof as more particularly pointed out in the appended claims.

Referring to the accompanying drawings, which illustrate what is at present deemed tol .be a Ipreferred embodiment of the invention,

Figure 1 is a plan view of a fan blade having a hub of the peculiar construction which embodies the essence of my invention.

Figure 2 is a side elevation of the same; Figure 3 is an end elevation thereof; gigure 4 is a perspective viewof the same; an

Figure 5 is a section taken'on the line 5 5 of Figure 1.

Referring in detail to the drawings, the two complementary fan blade portions 5 are, in the' illustrated embodiment of the invention, as most clearly shown'in Figure 3, disposed in relative position to each other at angles which are complementary to each other, the flat surfaces 7 in said view being desirably at an angle offorty degrees with relation to the LOS ANGELES, CALIFORNIA, ASSIGNOR T0 HvA-STER l' ing at right angles to the axis of rotation of l the blade as a whole. A l

The complementary blades 5 of the fan, together with a hub thereof, form an elongated twisted member, the central or hub portion of which is included in the twist, said hub por tion having its end surfaces flattened and elongated and bounded by compound curves resultant upon the general twist throughout the depth of the hub. At a point adjacent the leading edge of the curve 25 is the termination of the concavity 21 formed by the twist. This point lies adjacent to the intersection of the compound curve with the vertical axis of the blade.

The hub surfaces are bounded by similar compound curves 11 and 12 which are in opposite relation to each other. Each of said compound curves comprises a central portion 1ll (or 12) which is convex with-relation to the centeror axis of rotation of the fan as a whole and with relation to the flat hub surfaces 9 and 9a bounded thereby. This feature is most clearly observable in Figure 1 where the device is seen in plan.

As seen in Figure 1, the upper curve 11, at its upper end blends into a reverse curve 11b which, in turn, as seen in plan blends imperceptibly into the left hand edge of the main convex surface 8. On the opposite face of the blade the construction is identical except that the curve 11b terminates in the corresponding edge of the main ilat surface 7.

When viewed from a geometrical standpoint, the curves 11 and 12 may be considered as sine curves, the perpendicular dropped at the tangential intersection of said curves being at points 111 and 12p approximately upon a line drawn through the center of the axis of rotation parallel to the edges of the blades composing the fan. It is to be understood that the bottom curves are identical with the curves just described except that the arcs of the sine curve are in opposite relation to those just defined.

When considering' Figure 2, which is the side elevation of Figure 1, the perpendicular dropped'atthe tangential intersection of the arcs composing the sine curveoccurs at a point midway between the hub surfaces 9 and 9 on an axis parallel with the axis of rotation.

On the reverse side of Figure 2 the showing is the same except that the arcs of the sine curveare reversed as indicated by the dotted line in this view.

Outwardly bevond the extremities 26 of the flat hub surfaces 9 and 9a each blade of the fan is slightly convexed on one face from side to side and is of approximately uniform cross-section from these extremities to the outer end of the fan blade.

As seen in Figure 1, when the fan rotates in the direction indicated bv the two arrows, the flow of air will be in the direction indicated by the arrow at the right of Figure 2. If the twist given to the fan blades of Figure 1 were reversed, then rotation in the reverse direction to that indicated by the arrows in Figure 1 would still cause the air to iiow in the direction already stated with reference to Figure 2. It will, therefore, be obvious that when two oppositely twisted fans are mounted in spaced relation to each other upon the same shaft driven by a single motor, they may be used to draw air toward the midlleno'th of the shaft for delivery from a common-outlet..

As seen in Figure 4, alongside of the compound curve 11, at the right side of the fiat ub surface 9, extends a shallow groove, scallop or concavity 21 the bottom line of which extends along the right hand end of the shade lines which are located immediately to the right of said compound curve 11.

- The juncture of the Hat fan surface 7 with the hub portion, as well as the jun/cture of the convex surfaces 8 with the hub portion,

are arcuately formed as shown in Figure 4. The lateral extent of these arcs 30 is least at the top of the hub portion of the fan as seen in Figure 2, and progressively increases toward the other side of the hub through the angle of twist. It is found, in practice, that this construction overcomes the tendency of therapid rotation of the fan to create a negative or back current of air around the hub. A superior result is secured by this construction which prevents turbulence and back iow around the hub. e

Viewed in plan the hub portion of the fan is slightly narrowed from. side to side.

In the illustrated embodiment of the in` vention, a line drawn from one extremity to the other of the fiat hub surfaces 9 and 9B makes an angle of forty degrees with the longitudinal axis of the fan.

The direction of the central portion of the compound curve of edge 20. (see Figures 2 and 4) which extends from the extremity of one hub surface 9 to the opposite extremity of the other hub surface 9, makes an angle of forty degrees with the longitudinal axis of the fan.

The fan may be rotated effectively in the other direction thus adapting it for entraining or ejecting air through a window or other opening as desired.

In the elevation shown in Figure 2 it will be noticed that there is no cylindrical portion of a hub shown, which upon rotation would cause a direct trailing of air therearound, which is among the important objects of the invention to eliminate. On the contrary, instead of there being a cylindrical hub having a cylindrical side surface to interrupt the smooth flow of air, the air currents glide smoothly over the concavity 21 from end to end thereof in serpentine fashion thus adding to the efficiency of the fan and at the same time eliminating the noise usually caused by turbulence around the hub.

It must be understood that in the torsion produced in the rotation of the fan the lines of force through the fibers of the fan follow what would be the natural twist were a plane surface twisted from a flat through an angle of approximately ninety degrees.

With regards to the curves 25 and 25a seen in Figure l, the peculiar contour of line 20 shown in Figure 2 produces the depressions or dips bounded by said lines 25 and 25n aoA one of which is shown in Figure 2, whereby to create a means to cause the negative flow of air normally produced to take a course in the direction of the compound curve 11 along the concavity 21 aforementioned. This desirable result is enhanced by the cooperation of the intersection of said concavities 21, forming the compound curve 20, said curve,

by reason of its connecting the upper ex-V tremity of one blade'with the lower surface ofthe other blade, cutting the air tangentially and simultaneously 'giving the air a whirling motion and causing it to leave at the extremity of said concavity throughout the extent o the dip curve 25.

As clearly shown in Figs. 1 and 2, the leading and the trailing edges of each blade of the fan are equidistant from a plane lying in both the linear axis of the fan and the axis of rotation thereof, when the plane of rotation is considered to bisect the hub at its midlength, that is tosay, when such plane is regarded as being located at the mid-width of the fan as viewed in Fig. 2.

I claim:

1. A fan blade construction comprising two oppositely disposed blades, there being a flat tapered hub surface intervening between said blades, the leading edge of one blade be- .ing a continuation of one extremity of said hub surface, and the leading edge of the other blade being a continuation of the other extremity of said hub surface, said leading and trailing edges of each blade being equidistant from a lane lying in both the linear axis and the axis of rotation of the fan, said plane bisecting the hub at its mid-length.

2.'A fan blade construction comprisin a hub havin on each si e by two oppositely disposed geometrical sine curves the oints of tangency of which lie in `a plane which bisects the rotational axis of the fan at substantially 40 degrees;-two blade portions, formed as by a twist from the vertical whereby the slopes of said blades are disposed oppositely to each other and lie in planes approximately 40 degrees with the vertical, the leading and trailing edges of each blade also being equidisaxis and the axis of rotation of the fan, there y being alongside said geometrical sine curves a concavity or scallop which unites the sur- .fac'es of said hub with the surface of said blades, said concavity being ofrelatively small lateral extent from side to side at the a flat surface which is boun ed depth of each of said curved dips being at the midlength of the fan.

3. The matter contained in claim 2 and,

the apice's of said geometrical sine curves revolving 1n the same orblt, said aplcesbemg the origin of said concavity as well as the termination of the fiat portion of the blade adjacent to said concavity.

4. A fan blade construction comprising a hub and two oppositely disposed blades each having a concavity or scallop a portion of which extends spirally alongside `saidlhub,

said hub having a flat surface which is bounded on each side by two oppositely disposed compound curves, there being at each side of the fan a single curved dip opposite the hub portion thereof, said dip being positioned to narrow the central portion of the fan to aid the escape of the negative air current as it leaves the aforementioned concavit or scallop, the greatest depth of said curve dip being at substantially the mid-length'of the fan.

VWILLIAM HENRY CLAY NESS.

tant from a plane lying in .both the llinear l of the fan, near'the hub portion thereof, said l .dip being positioned to narrow the central portion of thev fan to aid the escape of the negative air current as it leaves the afore` l5 mentioned concavity or scallop, the greatest aol 

